In general, a freeroll doesn't play like a tournament for about the first hour or so. Expect goofy hands to do goofy things because folks are looking to chip up quick or move on to something else. Because of this I would expect to have to show the best hand to win, so be more selective in where you mix it up early.
My advice, play quality hands in the early part and let the loose play around you build your stack. Don’t get discouraged or angry at the beats when you get them. It’s a freeroll and sometimes you get stuck with the all-in-with-any-two-cards guy. Go into it expecting high variance and try to stick with made hands, not draws.
After about an hour you can start playing poker more like usual because the players that are left either went into it more seriously or they hit lucky and chipped up to the point where now it’s worth playing.
Final thought: Even if you're really deep, remember you're playing against folks that didn't pony up anything to play and going bust has no impact on their bankroll at all. There can still be some loose wild play, even late. You're usually able to spot these folks and pick your spots against them though. Sometimes they're behind big stacks and can be a nice ATM if you can get and make some hands because those are the folks that will often pay you off when you make a hand. Don’t be as afraid to bet into them thinking you’ll scare them off and won’t get max value.
Good Luck,